What is A Stirring Leaching Tank for Ore Dressing?

The stirred leaching tank is essential equipment in ore processing, designed to facilitate the dissolution of valuable minerals by uniformly mixing ores with solvents. This equipment typically consists of a large tank with an integrated stirring mechanism, which can be mechanical(mechanical stirring leaching tank), pneumatic(air stirring leaching tank), or a combination of both(air & mechanical combined stirring leaching tank). The design and operation of stirred leaching tanks vary based on metallurgical requirements, ensuring optimal extraction efficiency.

Let’s explore the different types of stirred leaching tanks and their unique features.

1. Mechanical Stirring Leaching Tank

In the mechanical stirring leaching tank, the high-speed rotating mechanical stirring paddle stirs the slurry. The propeller-stirring leaching tank is a commonly used mechanical-stirring leaching tank in production. When the propeller rotates rapidly, the slurry in the tank flows into the central slurry receiving pipe through each branch pipe, thus forming a vortex, and the air is sucked into the vortex so that the oxygen content in the slurry reaches the saturation value. At the same time, the rotation of the propeller pushes the slurry entering the receiving pipe to the bottom of the tank. Then it returns from the bottom of the tank to rise along the tank wall and enter the central slurry receiving pipe through the circulation pipe to realize multiple circulations of the slurry.

The characteristics of the mechanical stirring leaching tank are that the slurry can be stirred evenly and strongly and the air is continuously sucked into the slurry, so that the oxygen content in the slurry is higher, and it is more convenient to restart after shutdown, and the slurry will not press the propeller. In production practice, sometimes several vertical compressed air pipes are inserted into the tank, or air lifters are installed on the inner (outer) wall of the tank body to increase the oxygen content and stirring intensity in the slurry.

2. Axial Flow Pump Agitator Leaching Tank

The axial flow pump agitator leaching tank uses the rapid rotation of the impeller to suck the slurry at the bottom of the tank into the central tube and throw it upward to the conical reflector. Since the lower surface of the rotating reflector is conical, the slurry changes direction by 90 degrees after being thrown onto the conical surface of the reflector and withdraws to the surface of the slurry in the tank in a fan-shaped form. At this time, the surface area of ​​the slurry in contact with the air is large, and the slurry is filled with air. To prevent the slurry from deflecting at the center of the slurry surface due to the large amount of solids, which is not conducive to the impeller suction effect, a deflection plate is installed on the inner surface of the suction pipe. Due to the continuous rotation of the stirring paddle, the slurry is continuously discharged from the central tube suction port to realize the circulation of the slurry, so that the slurry is evenly distributed in the entire leaching tank and is often saturated with oxygen, thereby realizing the cyanide leaching of gold.

3. Air Stirring Leaching Tank (Tower)

The air-stirred leaching tank uses the pneumatic action of compressed air to achieve a uniform and strong stirring of the slurry in the tank. The upper part of the leaching tank is a tall column, and the bottom is a cone, which is mainly composed of a body, an intermediate tube, a compressed air pipe, a feed pipe, and a discharge pipe. During operation, the slurry enters the tank through the feed pipe, and the compressed air pipe goes directly to the lower part of the central tube. The compressed air rises in the central tube in a bubble state, making the density of the slurry in the central tube less than the density of the slurry in the annular space outside the central tube. As a result, the slurry in the central tube continues to rise, and the slurry in the annular space outside the central tube continues to fall, realizing the circulation of the slurry. The slurry stirring intensity can be adjusted by adjusting the compressed air pressure and flow rate. The slurry stirring of the compressed air-stirred leaching tank is very strong, which can make the oxygen content in the slurry close to the saturation value.

The air-stirred leaching tank can be operated intermittently or continuously. The former is that the slurry is discharged through the lower discharge pipe at the end of leaching, and the latter is that the slurry is discharged through the upper discharge pipe and enters the next leaching coffin.

4. Air & Mechanical Combined Stirring Leaching Tank

The air and mechanical combined stirring leaching tank is equipped with an air lifter and a mechanical rake in the center, or an air lifter is installed around the tank, and a slurry circulation pipe and a spiral stirring paddle are installed in the center of the tank. Therefore, it is also called a rake-type mixer leaching tank. The characteristics of this type of stirring leaching tank are a short tank body, no sediment at the bottom of the tank, high gold leaching speed, and low consumption of phthalates. The working principle is that the slurry enters the tank through the feed port located at the top of the tank, and settles to the bottom of the tank in layers in the tank. The slurry settled at the bottom of the tank gathers at the hollow lifting pipe mouth with the help of the rotation of the rake (I -4r/min). Under the action of compressed air, the concentrated slurry rises along the air-lifting pipe and flows into the two flow troughs with holes at its upper part, flows back to the tank through the flow holes, and the flow core rotates with the vertical axis, and the slurry is evenly distributed at the tip. The leached slurry is continuously discharged from the discharge port opposite to the feed port, thereby realizing continuous operation.

5. High-efficiency & Energy-saving Stirring Leaching Tank

The high-efficiency and energy-saving stirring tank is a new type of equipment developed in recent years. It has a double impeller structure. The air is diffused into the slurry through the air duct, air conversion valve, and hollow shaft, so that the slurry is suspended and maintains a high dissolved oxygen content, thereby ensuring the needs of the aeration leaching process conditions. This leaching tank has the advantages of low energy consumption, high efficiency, uniform stirring, and reliable operation. It is particularly suitable for stirring leaching in full mud aeration plants. At present, it has become the main leaching equipment of domestic carbon pulp plants.

Conclusion

Stirred leaching tanks play a critical role in hydrometallurgy, facilitating processes like gold cyanidation and copper leaching. From mechanical agitators to pneumatic towers and hybrid systems, each design offers unique benefits tailored to industrial needs. Modern advancements, such as energy-efficient dual-impeller tanks, further improve productivity while reducing operational costs.

For specialized applications, consulting an expert ensures optimal tank selection and process efficiency.